Field of the Invention
The invention relates to angle measuring tools, in particular to a tool capable of measuring full angles of an external corner and an internal corner.
Description of Related Art
In current industries of equipment manufacturing, teaching and scientific research and the like, angle measurement of product members is a common operation, but the full angle of an external corner (external protruding corner of a product) and an internal corner (internal corner inside a product) cannot be measured by adopting an existing protractor. Even when this can be achieved, the manufacturing process and assisting tooling structure of the protractor are very complex, leading to relatively high manufacturing cost and use cost. Existing full angle measuring tools, such as a full circle protractor disclosed in Chinese Patent Application (Publication Number CN204142117U), comprise a front scaleplate, a back scaleplate, a radius ruler and a semicircle ruler, wherein the semicircular ruler is smaller than the scaleplates in radius; the semicircle ruler is clamped between the two scaleplates; and the radius ruler is fixed between the scaleplates by a rivet. The semicircle ruler is provided with a chute which is provided with a slider having a pen hole. The semicircle ruler is provided with patterned modules, certain number of corresponding patterned modules with specified size need to be made first, and sample plates of different angles can be used for only once, so that a considerable amount of manpower and material resources are wasted; and such full circle protractor is more suitable for planar drawing and cannot be used for measuring full angles of the external corner and internal corner of a physical product.
Therefore, the invention develops a protractor capable of measuring full angles of the external corner and the internal corner.